A compound represented by the formula (XIV): particularly the formula (XV): is a compound useful as an intermediate for an anti-AIDS drug (International Publication No. 01/25240 and International Publication No. 99/67254). As a method for synthesizing a compound represented by the formula (XIV) or (XV), the methods described in International Publication No. 01/25240, EP-A-539192, Tetrahedron Letters, 27, p. 3715 (1986) and Tetrahedron Letters, 4, p. 505 (1995) are known. However, they use ozone oxidation and tributyltin hydride etc. having high toxicity, and are not industrially preferable methods. Of the above-mentioned references, International Publication No. 01/25240, EP-A-539192 and Tetrahedron Letters, 4, p. 505 (1995) comprise optical resolution of the obtained racemate with an enzyme and the like to give an optically active compound, whose relative configuration is represented by the formula (XV), and are inefficient. Recently, a method for directly synthesizing an optically active compound, whose relative configuration is represented by the formula (XV), has been reported in Tetrahedron Letters, 42, p. 4653 (2001). This method, too, uses an organic selenium compound having high toxicity, and is not entirely an industrial method.